I wish to be able to sum the downtime incurred on shift
for each product. I can do this if we only manufacture
the particular product once per shift. What I would like
is to sum the downtime incurred between a particular time.

e.g

Driwall 22:00 - 23:00
Hardwall 23:00 - 01:00
Driwall 01:00 - 05:00

In between these times there may be some downtime so I
want to know the actual time run on each product each time

Hope this makes sense

Pete